PROBING FOR EXOPLANETS HIDING IN DUSTY DEBRIS DISKS: DISK IMAGING, CHARACTERIZATION, AND EXPLORATION WITH<i>HST</i>/STIS MULTI-ROLL CORONAGRAPHY

Abstract

Spatially resolved scattered-light images of circumstellar (CS) debris in\nexoplanetary systems constrain the physical properties and orbits of the dust\nparticles in these systems. They also inform on co-orbiting (but unseen)\nplanets, systemic architectures, and forces perturbing starlight-scattering CS\nmaterial. Using HST/STIS optical coronagraphy, we have completed the\nobservational phase of a program to study the spatial distribution of dust in\nten CS debris systems, and one "mature" protoplanetrary disk all with HST\npedigree, using PSF-subtracted multi-roll coronagraphy. These observations\nprobe stellocentric distances &gt; 5 AU for the nearest stars, and simultaneously\nresolve disk substructures well beyond, corresponding to the giant planet and\nKuiper belt regions in our Solar System. They also disclose diffuse very\nlow-surface brightness dust at larger stellocentric distances. We present new\nresults inclusive of fainter disks such as HD92945 confirming, and better\nrevealing, the existence of a narrow inner debris ring within a larger diffuse\ndust disk. Other disks with ring-like sub-structures, significant asymmetries\nand complex morphologies include: HD181327 with a posited spray of ejecta from\na recent massive collision in an exo-Kuiper belt; HD61005 suggested interacting\nwith the local ISM; HD15115 &amp; HD32297, discussed also in the context of\nenvironmental interactions. These disks, and HD15745, suggest debris system\nevolution cannot be treated in isolation. For AU Mic's edge-on disk,\nout-of-plane surface brightness asymmetries at &gt; 5 AU may implicate one or more\nplanetary perturbers. Time resolved images of the MP Mus proto-planetary disk\nprovide spatially resolved temporal variability in the disk illumination. These\nand other new images from our program enable direct inter-comparison of the\narchitectures of these exoplanetary debris systems in the context of our own\nSolar System.\n